dicated a
prolate, others an oblate spheroid; the former figure may be popularly
represented by a lemon, the latter by an orange. To settle this, the
French Government, aided by the Academy, sent out two expeditions to
measure degrees of the meridian--one under the equator, the other as
far north as possible; the former went to Peru, the latter to Swedish
Lapland. Very great difficulties were encountered by both parties. The
Lapland commission, however, completed its observations long before the
Peruvian, which consumed not less than nine years. The results of the
measures thus obtained confirmed the theoretical expectation of the
oblate form. Since that time many extensive and exact repetitions of the
observation have been made, among which may be mentioned those of the
English in England and in India, and particularly that of the French
on the occasion of the introduction of the metric system of weights
and measures. It was begun by Delambre and Mechain, from Dunkirk to
Barcelona, and thence extended, by Biot and Arago, to the island
of Formentera near Minorea. Its length was nearly twelve and a half
degrees.

Besides this method of direct measurement, the figure of the earth
may be determined from the observed number of oscillations made by a
pendulum of invariable length in different latitudes. These, though they
confirm the foregoing results, give a somewhat greater ellipticity
to the earth than that found by the measurement of degrees. Pendulums
vibrate more slowly the nearer they are to the equator. It follows,
therefore, that they are there farther from the centre of the earth.

From the most reliable measures that have been made, the dimensions of
the earth may be thus stated:

Greater or equatorial diameter..............7,925 miles.
Less or polar diameter......................7,899 "
Difference or polar compression............. 26 "

Such was the result of the discussion respecting the figure and size
of the earth. While it was yet undetermined, another controversy arose,
fraught with even more serious consequences. This was the conflict
respecting the earth's position with regard to the sun and the planetary
bodies.

Copernicus, a Prussian, about the year 1507, had completed a book "On
the Revolutions of the Heavenly Bodies." He had journeyed to Italy
in his youth, had devoted his attention to astronomy, and had taught
mathematics at Rome. From a profound study of the Ptolemaic and
Pythagor